Modular power distribution systems are well known and comprise a plurality of modular electrical components which are connectable serially together to route power throughout an office area. These power distribution systems often include elongate power distribution assemblies (PDAs) which are mountable within raceways of conventional space-dividing wall panels, furniture or other static structures such as building raceways.
One known power distribution assembly comprises an elongate rigid mounting rail which extends substantially along the length of a wall panel and supports a pair of connector blocks or power blocks on the opposite ends thereof. The support rail houses elongate electrical conductors or wires therein which conductors define a plurality of electrical circuits and carry such circuits between said power blocks. In this regard, the conductors typically define multiple circuits of hot, neutral and ground conductors.
These conductors extend into the power blocks and have their opposite terminal ends electrically connected to individual conductor strips or terminals within the power blocks which define hot, neutral and ground terminals associated with each circuit. As such, the electrical circuits extend through the longitudinal length of the PDA wherein the power blocks include plug ports that provide access to the individual terminals and allow for plugging engagement of additional electrical system components thereto such as flex connectors, receptacles and the like.
Examples of such an electrical system are disclosed in U.S. Pat. Nos. 4,367,370 (Wilson et al.), 4,781,609 (Wilson et al.), 6,123,562 (King et al.) and 7,114,971 B1 (Johnson et al.), which are owned by the co-Assignee of the present invention, and the disclosure of which is incorporated herein by reference.
Furthermore, a commercially available electrical distribution system is sold by Haworth, Inc., the current Assignee, under the trademark Power Base. In the Power Base electrical system, the support rail of a PDA is an electrically-conductive metal rail which rigidly interconnects the PDA to one of the interior frame rails of a wall panel frame which frame rail extends along and defines one edge of a raceway.
The electrical circuits use at least one ground wire which is carried through the PDA and is grounded to the support rail. To accomplish grounding between the ground conductor and the support rail, the support rail is formed with a conductor channel which houses the conductors and a pair of foldable tabs along the intermediate length of the support rail, which tabs project downwardly into the conductor channel that is defined along the length of the support rail. The tabs are crimped or clamped about an exposed portion of an electrical conductor, and specifically, about the ground conductor. These tabs are manually crimped during assembly of the PDA to provide a suitable mechanical and electrical grounding connection between the ground conductor or wire and the support rail.
However, it is an object of the invention to provide an improved grounding connection between a support rail of a PDA and the electrical circuits carried therethrough.
The invention therefore relates to a PDA for such a modular electrical system which has an improved grounding feature which eliminates the manual crimping of tabs into engagement with the exposed conductor within the interior of the support rail channel.
The support rail is formed out of conductive metal and has a grounding arm or member formed integrally therewith in a unitary piece. Preferably, the grounding arm is initially formed as an axially extending extension of the support rail wherein the support rail has a longitudinal axis and the grounding arm essentially extends along the longitudinal axis when in an initial position. During assembly, the power block housings and interior contact terminals are assembled together in combination with the support rail which supports the power blocks thereon in downwardly depending relation. During this initial assembly, the grounding arm remains in the initial outwardly projecting position.
The housing of the power block further includes an access window which opens axially from a face of the power block and provides access to one of the contact terminals thereon, which said terminal is in the ground position and serves as a ground terminal.
More particularly, the ground terminals in the power blocks are connected to the opposite ends of an intermediate ground conductor or wire which extends between the power blocks, wherein the conductor ends and the ground terminals are internally connected together within the power block housings. The power blocks also include plug ports on the opposite side faces thereof which allow for the connection, for example, of a receptacle, which receptacle is both mechanically plugged into the power block and has its own internal conductors which electrically connect to the hot, neutral and ground terminals of the PDA.
As to the grounding arm, this grounding arm has a bendable strap, and a pair of jaw-like connector flanges, which project downwardly from the grounding arm when in the initial, outwardly-extending position. As the grounding arm is bent downwardly to an engagement position oriented at a right angle to the initial position, the grounding flanges are inserted sidewardly into the corresponding access window to engage the grounding terminal contained within the power block. The grounding flanges have a jaw-like construction with a narrow mouth defined therebetween which allows for tight fitting receipt of an edge of the grounding terminal. The power block housing also includes retainers which engage with the grounding arm during bending to retain the grounding arm in the bent, engaged position.
This grounding arm also may be formed as a separate strap having a pair of the jaw-like connector flanges which are provided at two spaced apart locations and which are separate from the support rail as well as the power blocks in the initial, disengaged position. As the grounding arm is moved to the engagement position, preferably oriented at a right angle to the support rail, one set of the grounding flanges are inserted sidewardly into the corresponding access window to engage the grounding terminal contained within the power block, and the other set of grounding flanges is fitted sidewardly onto an edge portion of the support rail. Each set of the grounding flanges has a jaw-like construction with a narrow mouth defined therebetween which allows for tight fitting receipt of the edge of the grounding terminal in the access window and the edge portion of the support rail which is preferably accessible outside of the power block. The power block housing also includes retainers which engage with the grounding arm during positioning to retain the grounding arm in the engaged position.
In this manner, the conductive support rail can be readily interconnected with an internal ground terminal merely by downward bending of the grounding arm. This improved PDA allows for improved manufacturing and a positive connection between the support rail and a ground terminal contained within a power block.
Other objects and purposes of the invention, and variations thereof, will be apparent upon reading the following specification and inspecting the accompanying drawings.
Certain terminology will be used in the following description for convenience and reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement and designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.